An electric linear actuator converts rotary motor torque — or piezo, pneumatic, or electromagnetic input — into controlled straight-line motion, and the selection flow reduces to four gates: drive principle, force/velocity envelope, guidance/bearing class, and feedback resolution [S3].
Lead-screw, ball-screw, belt-driven, direct-drive linear-motor, voice-coil, and piezo actuators split the field; each has a defined resolution, force, speed, and duty envelope, and pairing the wrong one to the load profile is the most common cause of premature failure in fielded machines [S2][S3].
Stage Material Trade-Off: Steel vs Aluminum vs Brass vs Granite
Aluminum's specific stiffness (E/ρ = 108) exceeds steel's (101), and its thermal conductivity (104 BTU/hr-ft-°F) is roughly 6.7× steel's, which is why anodized aluminum is the default for stages exposed to thermal gradients; the limit is high-vacuum service, where anodized pores outgas and steel or stainless is mandatory [S1]. Steel gives ~3× the modulus of aluminum (28 vs 10.5 Mpsi) and roughly half the thermal expansion (5.6 vs 12.4 µin/in/°F), so it wins for stiffness-critical and thermally stable builds, at the cost of slower machining and rust risk that forces plating or stainless alloys [S1]. Brass sits in a niche: density 0.307 lb/in³ (heavier than steel), low specific stiffness (45.6), but useful as a dissimilar wear surface against steel lead-screws to prevent galling, and diamond-turnable for ultra-smooth bearing seats [S1]. Granite (α = 4 µin/in/°F, the lowest in the table) is reserved for metrology bases where thermal drift must be suppressed at the structural level [S1].
Drive Principle Comparison: Screw, Belt, Voice-Coil, Piezo, Linear Motor
Ball screws and lead screws provide high thrust and good accuracy for general automation; belt drives extend stroke cheaply but limit precision; direct-drive linear motors and voice coils remove belts and screws entirely, cutting backlash and friction for high-speed or high-dynamics moves; piezo actuators deliver nanometer and sub-nanometer resolution over short travel [S3]. The decision matrix reads: screw-driven for high force at moderate speed and stroke, belt-driven for long travel at low cost and moderate accuracy, voice-coil for high acceleration over short stroke, linear-motor for high speed with zero backlash, piezo for sub-µm resolution under low load [S2][S3].
Force, Stroke and Moment Load: The Numbers That Actually Fail
Oriental Motor's published method treats an electric linear actuator as a linear mechanism + motor combination and flags moment loads from gravity, acceleration, and deceleration as the primary damage mechanism — verifying that applied moments stay within the actuator's rated envelope is the non-negotiable gate before sizing motor power [S2]. Wuxi Hongba's standard 12 VDC brush mini electric actuator publishes a 2000 N thrust rating at sample-grade pricing, a useful benchmark for the low-cost end of the duty envelope; Changzhou HAX and similar Jiangsu OEM lines fill the mid-range from US$127–198 per piece at 1-piece MOQ [S6][S4]. Resolution and accuracy scale with feedback: linear encoders, interferometers, and capacitive sensors compensate for thermal drift and load variation in real time, and the closed-loop choice should match the application's required positioning tolerance, not the actuator's open-loop step resolution [S3].
Guidance and Bearing Class: Air, Crossed-Roller, Flexure, Profile Rail
Air bearings give frictionless, wear-free motion and the best geometric accuracy, but require clean compressed air and a flat reference surface; crossed-roller guides deliver high stiffness and load capacity in a compact envelope and dominate mid-range industrial stages; flexure guides eliminate backlash and friction for limited-travel nanopositioning where stick-slip would corrupt the result; profile-rail linear guides handle dirty industrial environments and long travels where recirculating ball contact is acceptable [S3]. For stages that also need a structural support, linear bearings cover the sleeve-bearing and bushing category used in lower-duty manual or low-speed electric builds. The crossed-roller class is the workhorse for motorized stages that need both stiffness and moderate travel without air supply.
Feedback and Control: Why Resolution Alone Misleads
Open-loop step resolution is a marketing number, not a positioning spec; closed-loop feedback with a linear encoder or interferometer defines the actual accuracy and repeatability a system will hold under load and thermal disturbance [S3]. Settling time, velocity stability, following error, and control bandwidth are the metrics that decide cycle time in semiconductor inspection, photonics alignment, and precision assembly — a 1 µm-resolution encoder with poor servo tuning will underperform a 100 nm-resolution encoder in a well-tuned loop [S3]. For long-stroke or multi-axis systems, linear modules package the actuator, guide, drive, and feedback into a single shippable unit, cutting integration time at the cost of some customization. For the simplest short-stroke pick-and-place or valve actuation, a linear actuator without an external encoder is fine, but once the application enters metrology, alignment, or any regulated process, closed-loop feedback is mandatory.
Application Fit and Duty Cycle: When NOT to Pick an Electric Linear Actuator
Electric linear actuators fit clean, controlled environments — semiconductor tools, medical devices, optics benches, factory automation cells, antenna positioners, and small-format motion stages — and they are the wrong pick for explosive atmospheres without Ex-rated certification, for sub-nanometer stability where piezo flexure stages are required, or for very long horizontal travels (>5 m) where rack-and-pinion or linear-motor gantrys dominate on cost [S3]. High-cycle pneumatic or hydraulic cylinders beat electric actuators on raw force density and intrinsic explosion-safety when the duty cycle is short, the environment is wet or dirty, and energy efficiency is secondary to peak thrust; the drylin®-class polymer-bearing electric actuators are explicitly aimed at grease-free, low-maintenance industrial service, not at the high-shock, high-contamination edges of heavy industry [S2]. Verification of fit should run through a four-gate checklist: (1) drive type matched to force/velocity/resolution, (2) moment loads within published limits under worst-case acceleration [S2], (3) guidance class compatible with cleanliness and stroke, (4) feedback resolution and bandwidth aligned to the process tolerance.
Sourcing Signals and What to Track Next
Current OEM pricing from Jiangsu-based manufacturers sits in two clusters: 12 VDC brush mini actuators at US$15–46 per piece for low-thrust commodity duty, and mid-thrust 2000 N-class industrial actuators at US$127–198 per piece, both at 1-piece MOQ with ISO 9001:2015, ISO 14001, and ISO 45001:2018 certifications on the audited-supplier tier [S4][S6]. Trackable next signals: Newport's motorized linear actuator compatibility tables (linked to its stage-to-actuator selection guide) for cross-vendor integration questions, and the drylin® screw-driven and belt-driven product lines for grease-free industrial retrofits [S1][S2][S5]. For related electric-motion component decisions, the electromagnetic brake selection six-gate spec map provides a parallel decision framework when the actuator must hold position under power-off conditions, and the electromagnetic brake buying guide 2026 covers the source/side that pairs with most industrial linear actuator installations.